Designing a Better Windmill

Three innovative designs show you don’t need a giant
turbine to harvest the wind’s energy.

Windmills might be a source of renewable, clean energy, but their
design limits them to rural areas with high-speed winds. Shadow-flicker and
noise are common complaints of those who have lived near the giant structures,
and the possibility of flying ice or a falling tower makes them unthinkable in
high-density areas. Luckily, elevated turbines aren’t the only way to catch the
power of wind. For Sierra, David
Ferris highlights three
innovative designs suited for use in different environments.

UrbanA 25-square-foot structure designed to sit atop tall
buildings, the Vibro-Wind Panel (top) is a great fit for urban areas. To capture energy, foam blocks wobble in the wind. One of the panel’s lead developers, Frank
Moon of Cornell University, estimates that in the right
conditions the Vibro-Wind Panel could compete with a solar panel of similar size.

Hot and DryStill in the concept phase, the Solar Wind Downdraft Tower (right) would create its own wind by
spraying mist, delivered by solar-powered pumps, at the top of a 2,200-foot
tower. The tower’s height would make the Downdraft the tallest building in America, but the
sinking, evaporating mist could create enough wind, once channeled through
tunnels and turbines, to power 1.6 million homes.

Disaster Areas Perhaps the most versatile of these models, the Sheerwind
Invelox (left) gathers wind from any direction, funneling and
forcing the air through a turn to accelerate its speed. Finally, the air runs past a
turbine, which converts the energy. The Invelox can produce the same amount of power as
a commercial wind tower at a third of the height—60 to 90 feet tall—and gather
breezes travelling under two miles per hour, far less than the speed required
to spin the blades of a giant windmill. Invelox inventor Daryoush Allaei has designed a collapsible model made of aluminum and fabric that can be air-dropped for
assembly in disaster areas or military outposts. Of course, a more durable
version can be used to supply energy to established buildings
and communities as well.